New York: Concerned over the killing of 16 Afghan civilians by a US soldier, an incident coming days after copies of Quran were burnt, American officials feel such episodes will "embolden" the Taliban and create an "instant windfall" for the group.

"The outrage from the back-to-back episodes of the Quran burning and the killing on Sunday of at least 16 Afghan civilians imperils what the Obama administration once saw as an orderly plan for 2012 to speed the training of Afghan forces so that they can take the lead in combat missions, all while drawing the Taliban into negotiations to end more than a decade of constant war," an analytical piece in the New York Times said.

As details of the shooting of the Afghan civilians, including nine children, emerged, American military and civilian officials said such events would "embolden the hard-liners within the Taliban, who oppose negotiations with a force that is leaving the country anyway and who want to use the next two years to appeal to the understandable national allergy to foreign occupation," the Times said.

Officials say two major concerns grow out of such episodes, making some in the Obama administration wonder whether the US President's speeded-up pullout plan should be hurried up even more.

The first concern is regarding the training mission. After the Koran burning, there were fears in the military that it would become harder for American or NATO military trainers to move freely among an Afghan Army force of 350,000 troops, most of whom are poorly trained.

Fearing for their own safety, the trainers will bring along larger security details, to assure they do not fall under attack.

The second concern is even harder to assess, the Times said.

"The Taliban will conclude that events like this will, in the end, only increase the pressure on the United States to get out quickly.

"Till now efforts to bring the Taliban to the negotiating table in Qatar, where Ambassador Marc Grossman and other American diplomats are seeking to arrange talks, have gone painfully slowly," it said.

"The fear", one American military official said, "is that all these incidents, taken together, play into the Taliban's account of how we treat the Afghan religion and people.

"And while we all know that's a false account — think how many the Taliban have killed, and never once taken responsibility — it's a very hard perception to combat".

It is episodes like this, one American official said, "that create an instant windfall for the Taliban", at just the moment that the US is trying to persuade them that their cause is all but lost.

The New York Times analysis said President Obama and his aides had once hoped that with the troops pullout, only a couple of years away, they would have cemented the narrative that the Taliban were a spent force being pounded into peace negotiations and recognising that they could never retake control of the country.

Testifying before the Senate last week, Admiral James Stavridis, the overall commander of NATO forces, had said, "I believe we will have an enduring partnership between NATO and the Republic of Afghanistan" beyond 2014.

Given the urgency with which Washington reacted to the news of the killings of the Afghan civilians, the Times said it underscores the "depth of the concern that such an agreement could become harder and harder to sell to Hamid Karzai, the Afghan President".

American counterinsurgency experts said the shootings could have a devastating impact on the painstaking efforts by the American and other troops over the past year to win the trust of Afghan villagers.

"It takes months and months to build the trust of the local populations, and then something like this happens and it’s gone, literally overnight," senior political scientist Seth Jones said.